netacc-gpn-4-201-239:rails ranagol$ rails hello
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:777:in `report_activate_error': RubyGem version error: rack(1.5.2 not ~> 1.4.5) (Gem::LoadError)
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:211:in `activate'
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:246:in `activate'
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:245:in `each'
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:245:in `activate'
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:246:in `activate'
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:245:in `each'
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:245:in `activate'
	from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems.rb:1056:in `gem'
	from /usr/bin/rails:18